Structural archaeologist Geoff Carter's radical view of building in the ancient world, especially the archaeology of the lost timber built environment of Southern England. It is new research into of prehistory of architecture, available in a series of articles that are designed to be read in order, and to be accessible to the non-specialist - and there is even some humour

13 October, 2011

Marcus Vitruvius Pollio, better known as Vitruvius, is one of those rare individuals from the ancient world whose thoughts and ideas have survived him. He was a contemporary of Julius Caesar, and wrote the only significant surviving book about Roman architecture. His book, De architectura, known as The Ten Books on Architecture, is dedicated to emperor Augustus, and provides a unique insight into the thoughts and perceptions of architect living two thousand years ago.[1]

The passage of time has effectively shredded the vast the majority of written material from the ancient world, so it is difficult to set Vitruvius in a wider context. Most of what we know about him has been second-guessed from his book, and his precise origins and even his name remain the matter of debate.[2]

It is thought that he served a soldier with Julius Caesar, probably in the artillery, and then worked as an architect after he retired from the army.

However, following its rediscovery in 1414, a series of translations in the fifteenth and sixteenth centuries made De architectura an important text for the Renaissance. It was central to the understanding remains of the classical world, and consequently, influential in the subsequent development of architecture.

After Vitruvian Man by Leonardo da Vinci circa 1487.

[based on Vitruvius ideas about proportion] [3]

The scope of the Ten Books, covering architecture, civil and mechanical engineering, as well as all manner of matters arising, including how to make a ballista, illustrates the range of activities undertaken by ‘architects’ in this period.

We are going to concentrate on Book II, which concerns raw materials, and specifically chapter IX, which is about timber.

Rationality and the elements

This work not being intended for a treatise on the origin of architecture, that origin, and the degrees by which it passed to its present state of perfection, is only incidentally mentioned.

Marcus Vitruvius Pollio:

de Architectura, Book II [0.9][4]

Sadly, Vitruvius is not going to tell us much about of prehistoric timber building, although he does mention it; he is interested in modern state of the art architecture, albeit in best aesthetic traditions of the ‘classical’ world. Predictably, ancient texts written in a dead languages, even one as well known as Latin, present translation problems, particularly with technical vocabulary. We do not have many texts that discuss trees, so it there is room for confusion as to precisely which species the text refers to.

The importance of chapter IX is that it illustrates not only what Vitruvius knew about timber, but also how he rationalised their various properties and understood trees in general. Importantly, Vitruvius can rationalise the material world. It all makes sense to him; it is not subject to divine whim and superstition. He is anxious to back up his explanations with examples and parallels from nature.

As might be expected, his observations about the properties and uses of different types of timber are perfectly valid; unfortunately, by contemporary standards, his explanations of these characteristics are not. The following is a good example of how Vitruvius looks in translation, and why I intend to paraphrase much of the rest of the chapter.

5. The qualities of trees vary exceedingly, and are very dissimilar, as those of the oak, the elm, the poplar, the cypress, the fir, and others chiefly used in buildings. The oak, for instance, is useful where the fir would be improper; and so with respect to the cypress and the elm. Nor do the others differ less widely, each, from the different nature of its elements, being differently suited to similar applications in building.

6. First, the fir, containing a considerable quantity of air and fire, and very little water and earth, being constituted of such light elements, is not heavy: hence bound together by its natural hardness it does not easily bend, but keeps its shape in framing. The objection to fir is, that it contains so much heat as to generate and nourish the worm, which is very destructive to it. It is moreover very inflammable, because its open pores are so quickly penetrated by fire, that it yields a great flame

Marcus Vitruvius Pollio:

de Architectura, Book II [10.5-6][4]

Vitruvius tells that fir, above [5], what a modern carpenter might generically call ‘deal’, is light, strong, and suitable for framing, but is susceptible to worm [termite] attack and is flammable; all this is as true now as it was then. However, what has changed is the way we rationalise these properties and fit them into the wider material world.

In the classical world, the properties of matter were often described in terms of the four elements, water, air, earth and fire, with room for a more spiritual fifth element.[6] Not only was this the system that developed into what we know as alchemy, but also it was at the root of much rational thinking throughout ancient Eurasian culture. This basic four/five element system seems to be present in Mesopotamia in the Bronze Age, and is evidenced in India, Tibet, China, and Japan, from where it subsequently developed into various complex systems of understanding. [below]

The widespread nature of this system suggests it developed fairly early, and probably in the Fertile Crescent, although from a classical perspective, it was formalised by a Greek philosopher called Empedocles, from Agrigentum in Sicily (c. 490–430 BC). [7]

There is no point in discussing the nature of this understanding further, and from now on I will edit out this material and paraphrase his observations about the properties and uses of timber. The important point to appreciate is that Vitruvius believes he has a rational perspective; today we would call it scientific. But that would be inappropriate in this context, and with the benefit of technical hindsight, we know just how wrong he turned out to be.

Two thousand years ago, Marcus Vitruvius Pollio was master of his craft, educated, well read, and was writing from the familiar perspective of someone living at a time of unparallel progress and technological achievement, in a culture at the top of its game.

Felling trees

As a builder, one of Vitruvius’s principle concerns is what we would call the moisture content of the timber, and the importance of drying or seasoning it before use, reducing the risk of cracking and distortion. He tells us that timber should be felled from early Autumn onwards, and well before spring, which is much as expected, but his method of felling is very different from the modern approach.

3. In felling a tree we should cut into the trunk of it to the very heart, and then leave it standing so that the sap may drain out drop by drop throughout the whole of it. ……. Then and not till then, the tree being drained dry and the sap no longer dripping, let it be felled and it will be in the highest state of usefulness.

Marcus Vitruvius Pollio:

de Architectura, Book II [9.3] [4]

In other words, the tree is killed, but left standing until dry enough for use.

In his discussion of the importance of draining the sap from wood before use, he mentions the practice of tapping the trunks of trees specifically to extract the sap.

. . .When these are tapped at the base and pruned, each at the proper time, they pour out from the heart through the tapholes all the superfluous and corrupting fluid which they contain, and thus the draining process makes them durable.

Marcus Vitruvius Pollio:

de Architectura, Book II [9.4] [4]

His text is not specific as which to types of tree were tapped, although this may have been obvious to his readers. Trees have traditionally supplied a range of oils and resins, and maple syrup is a good modern example of the technique. It is a use of trees that is hard for archaeologist to detect, except through chemical analysis.

One of the most intriguing examples of the use of resins in the ancient world, comes from the hair of an Iron Age bog Body from County Meath, Ireland.

Clonycavan man from [left] met an unpleasant and violent end between 392 BC and 201 BC, and analysis of his Mohawk hair style discovered it was held in place with a preparation made of plant oil and pine resin imported from south-western France or Spain.[8]

Softwoods

Fir: We have already quoted Vitruvius' ideas about this tree, noting that is light but stiff, and useful f0r frameworks, but is susceptible to termite attack, and is easily flammable, disadvantages that limit its applications in building.

He then discusses the nature of fir as a timber distinguishing between types of timber: ‘knotty’, which is derived from the upper part of the trunk, and ‘clear’ which was from the lowest 20 feet.

The lowest part, after the tree is cut down and the sapwood of the same thrown away, is split up into four pieces and prepared for joiner's work, and so is called "clearstock."

Marcus Vitruvius Pollio:

de Architectura, Book II [9.7] [4]

This basic conversion produces the best quality timber, which we would call ‘boxed heart’, [right], which is then is further split into quarters, presumably through the centre, providing squared timber suitable for the framing work Vitruvius describes. It is worth noting that a great deal of less valuable timber would be used in temporary scaffolding and the formwork required for the creation of masonry and concrete structures.

In the following chapter [X] he explains why the situation and aspect are important, in particular why;

...the lowland firs,being conveyed from sunny places, are better than those highland firs, which are brought here from shady places.

Marcus Vitruvius Pollio:

de Architectura, Book II [10.2] [4]

This emphasises the craftsman’s insistence on the highest quantity materials, a prime consideration in the choice of structural timbers. Anyone choosing timber has the same concerns about stability, straightness of the grain, presence of knots, and susceptibly to insect attack, although the latter is becomes less important in northern Europe.

Cypress and pine: While these timbers are apt to warp, their pungent sap makes resistant to insect attack, and this durability in greatly valued in buildings. These trees also produce useful resins.

The cedar and juniper tree: Vitruvius tells us that these timbers are also resistant to termite attacks, and hence, very long-lasting when used in buildings. The cedar is also the source of an oil used to treat things like paper to make it resistant to rot and insects, (cedrium).

The cedar grows chiefly in Crete, Africa, and in parts of Syria. It is notably straight grained, and has been used for the roof timbers of famous temples buildings like the Temple of Diana at Ephesus. [9]

Hardwoods

Oak [quercus ]: Oaks are a very widespread species of tree and Vitruvius mentions three, producing timber of differing utility. While common oak [quercus] has a tendency to warp and crack in moist condition, it is very long lasting when used in underground.

Another oak [aesculus] is very useful within buildings, but because of its propensity to rot, it is unsuitable for exterior work.

Turkey oak [cerrus] and beech[left] also readily decay and are only suitable for interior use.

Alder: Alder is another familiar tree, which Vitruvius tells us was grown, then as now, close to riverbanks. He notes that it is of little value for buildings, but is exceptionally durable wood when used under water, and was widely used in his time for piles, notably in Ravenna.

White and blackpoplar, willow, lime [right]: These are light, but still relatively stiff woods. They are white in colour and particularly suitable for carving.

Hornbeam: Vitruvius tells us that hornbeam is very strong and easily worked timber used for yokes by the Greeks.

Elm [left] and ash; These he regards as timbers as too flexible for use in building; however, he says that when well seasoned, they can make good treenails and pegs for securing joints:

‘…….supply a strong material for dowels to be used in joints and other articulations’.

Marcus Vitruvius Pollio:

de Architectura, Book II [10.11] [4]

The larch:

I have left the larch till last because Vitruvius has much to say on the value of larch, both for it is resistant to termites and rot, and particularly its lack of flammability. Wood that does not easily catch fire has obvious advantages in a built environment. Larch was available in long straight lengths with a clear grain, and was also the source of a liquid resin, good for consumptives. Vitruvius implies that until recently the Larch was known, or at least used, only on the banks of the river Po and the shores of the Adriatic; he then recounts the following story involving Julius Caesar [below right]. [10]

It is worthwhile to know how this wood was discovered. The divine Caesar, being with his army in the neighbourhood of the Alps, and having ordered the towns to furnish supplies, the inhabitants of a fortified stronghold there, called Larignum, trusting in the natural strength of their defences, refused to obey his command. So the general ordered his forces to the assault.

In front of the gate of this stronghold there was a tower, made of beams of this wood laid in alternating directions at right angles to each other, like a funeral pyre, and built high, so that they could drive off an attacking party by throwing stakes and stones from the top. When it was observed that they had no other missiles than stakes, and that these could not be hurled very far from the wall on account of the weight, orders were given to approach and to throw bundles of brushwood and lighted torches at this outwork. These the soldiers soon got together.

The flames soon kindled the brushwood that lay about that wooden structure and, rising towards heaven, made everybody think that the whole pile had fallen. But when the fire had burned itself out and subsided, and the tower appeared to view entirely uninjured, Caesar in amazement gave orders that they should be surrounded with a palisade, built beyond the range of missiles. So the townspeople were frightened into surrendering, and were then asked where that wood came from which was not harmed by fire. They pointed to trees of the kind under discussion, of which there are very great numbers in that vicinity. And so, as that stronghold was called Larignum, the wood was called larch.

Marcus Vitruvius Pollio:

de Architectura, Book II [9.15-16]

I see no reason to doubt the events portrayed. It is an entirely plausible insight into Roman military tactics, and besides, it would be foolish to make up such a story, especially about an incident in the recent past, which would have many other witnesses. It is perhaps not unreasonable for people living in Rome to be unaware of particular tree species in the foothills of the Alps.

Crediting Caesar with their ‘discovery’ seems entirely in keeping with an imperialist mindset, and not out of tune with the sycophantic tone appropriate in a book dedicated to an emperor, reigning by virtue of being Caesar’s ‘heir’.

Throughout, Vitruvius is fulsome of his praise of the larch.[left]Perhaps significantly, Vitruvius chooses this point in the narrative to push the idea of importing larch into Rome, to be used for fire resistant eaves to protect buildings and prevent fires from spreading. We will likely never know if this civic-minded innovation was in someone’s pecuniary interest, or if it was adopted.

Discussion

Vitruvius is just the sort of person theoretical structural archaeology studies: He is an architect and builder in the widest possible sense: anything involving the fundamental modifying of the environment is his concern.

In many ways, what he knows is exactly what I would expect him to know about timber.His concerns about structural stability and strength are balanced against environmental performance, and in particular, resistance to termite attack, illustrating the regional nature of architectural systems. Termites have a significant impact on material culture in those areas where they occur, in particular on the choice and potential utility of timbers, but further north, this becomes much less of a concern.

The larch is a familiar conifer that loses its needles in winter

Vitruvius' interest in the potential of larch as a fire-resistant timber shows not only that the danger of the spread fire in urban areas was a concern for architects, but also illustrates a building culture that was dynamic and open to innovation, despite its “present state of perfection”. The larch story also illustrates the slightly parochial nature of knowledge when judged against modern standards: That Romans should be unfamiliar with the properties of trees growing a few hundred miles away is probably a reflection of the difficulty of trading a bulk cargo like timber.

However, cedar, greatly favoured by Vitruvius, and a timber of renown throughout the ancient world, would have been an expensive import.

The Oak that comes most highly recommended is aesculus, but unfortunately the meaning of this term is still the matter of debate.[11] It could be sessile [Q. petraea] or perhaps Italian /Hungarian oak.[right; Q. frainetto] [12].

He seems to be most familiar with the local fir trees [Abies alba], which then, as now, was probably the standard utility wood. As well as its more obvious uses in buildings, we should not forget that timber was also used for scaffolding, as well as for formwork for some of the more elaborate masonry and concrete forms used in Roman architecture.

It is notable that only those trees with a direct application to building are discussed, other applications of the timber and many economical important and useful species are not mentioned at all.[13] In all cases the properties are well observed, and as expected, are still the basis of their traditional and contemporary uses.

The use of selected materials for pegs and treenails, ash being very resilient, and elm very tough, is illustrative of how craftsmen seek out the optimum materials for each application. It is the very essence of woodworking that each component of a fabrication, whether a building or a ballista [below left], would be made from a timber with the optimum set of properties.Hornbeam is not a timber traditionally associated with building, but because of its toughness, was traditionally used for things like woodwork in machinery and pulley-blocks. This reminds us of Vitruvius background in military engineering and the wider field that ‘architecture’ embraced.

He would have been a very useful bloke to have around, and the application of such skills to the battlefield was one of the Roman armies’ principle advantages in the field. They out-engineered their opponents. For example, the range of their artillery upset many of their enemies’ most basic strategic assumptions.

In the literate Mediterranean world we can readily accept architects, but it is not something that has been considered for the illiterate peoples to the north. It is my contention that most societies had people with this skill set; they were the engineers that were out-engineered by the Romans, the builders responsible for domestic, agricultural and public building before the Roman occupation.

Vitruvius clearly regards his belief system to be a rational explanation of the physical world. His observations are perfectly valid; it is only the system he uses to connect and explain them, that falls short of modern standards. While the way we rationalise has changed, the need of craftsmen for a rational understanding of their materials and processes has not.Vitruvius would have readily acknowledged that the Greeks had originated his classical elemental science; however, surely their philosophy,like their stories, had an aural and preliterate past. What they chose to write down was not necessarily knowledge created specifically for the purpose, or the direct result of literacy.

It seems reasonable that fundamental aspects of ‘classical’ thought had much deeper and older roots. The widespread nature of the basic "water, air, fire, and earth" elemental approach to the material world, and its early appearance in a variety of literary traditions, suggests that it was part of shared preliterate system developed early in the Neolithic. It was perhaps one aspect of a complex set of skills and knowledge that underpinned the technological aspects of the Neolithic and subsequent agricultural cultures, both literate and illiterate.